Browse free open source Calculators and projects for Windows below. Use the toggles on the left to filter open source Calculators by OS, license, language, programming language, and project status.

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  • 1
    PeaZip

    PeaZip

    Free Zip software and Rar extractor

    PeaZip is a free archiver tool. The application provides an unified, natively portable, cross-platform file manager and archive manager GUI for many Open Source technologies like 7-Zip, FreeArc, PAQ, UPX. Create: 7Z, ARC, Brotl, BZip, GZip, PEA, TAR, WIM, XZ, ZPAQ, ZIP, Zstandard files and more Open and extract 200+ file types: ACE, CAB, DEB, ISO, RAR, ZIPX and more Features of PeaZip includes extract, create and convert multiple archives at once, create self-extracting archives (sfx), split files, strong encryption with two factor authentication, encrypted password manager, secure deletion, find duplicate files, calculate hashes, export task definition as command line script.
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    Downloads: 1,468 This Week
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  • 2
    Windows Calculator

    Windows Calculator

    A simple yet powerful calculator that ships with Windows

    Calculator is the open source version of the Microsoft Windows Calculator application. It is a modern Windows app written in C++ and C#, offering standard, scientific, and programmer modes, unit/currency conversion, date calculations, and history/memory operations. It ships preinstalled with Windows and is actively developed on GitHub. Standard Calculator functionality, which offers basic operations and evaluates commands immediately as they are entered. Scientific Calculator functionality, which offers expanded operations and evaluates commands using the order of operations. Programmer Calculator functionality, which offers common mathematical operations for developers, including conversion between common bases.
    Downloads: 135 This Week
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  • 3
    Integrated Development Environment for some microcontrollers based on 8051(e.g. AT89S8253). Supported languages are Assembly and C. It has its own simulator, assembler, editor and many other tools. See the project web site for more details and the newest updates.
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    Downloads: 348 This Week
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  • 4

    TILP - TI Linking Program

    TI graphing calculators <-> computer communication software

    TILP (formerly GtkTiLink) can transfer data between Texas Instruments graphing calculators and a computer. It works with all link cables (parallel, serial, Black/Gray/Silver/Direct Link) and it supports the TI-Z80 series (73..86), the TI-eZ80 series (83PCE, 84+CE), the TI-68k series (89, 92, 92+, V200, 89T) and the Nspire series (Nspire Clickpad / Touchpad / CX, both CAS and non-CAS). The project is now managed on Github, https://github.com/debrouxl/tilp_and_gfm . It uses the libti* libraries, https://github.com/debrouxl/tilibs . Install script for *nix: https://github.com/debrouxl/tilp_and_gfm/blob/master/tilp/trunk/build/scripts/install_tilp.sh
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    Downloads: 320 This Week
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    CRC RevEng

    CRC RevEng

    Arbitrary-precision CRC calculator and algorithm finder

    CRC RevEng is a portable, arbitrary-precision CRC calculator and algorithm finder. It calculates CRCs using any of the 113 preset algorithms, or a user-specified algorithm to any width. It calculates reversed CRCs to give the bit pattern that produces a desired forward CRC. CRC RevEng also reverse-engineers any CRC algorithm from sufficient correctly formatted message-CRC pairs and optional known parameters. It comprises powerful input interpretation options. Compliant with Ross Williams' Rocksoft(tm) model of parametrised CRC algorithms.
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    Downloads: 134 This Week
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  • 6
    Calculator to compute message digests, checksums for files, as well as for text and hex strings.
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    Downloads: 333 This Week
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  • 7
    teemIP - CMDB & DDI solution

    teemIP - CMDB & DDI solution

    teemIP : Open source IPAM & DDI solution with CMDB integration.

    teemIP is an open source, web-based IP Address Management (IPAM) and DDI solution built on the iTop framework. It provides comprehensive IP management: IPv4/IPv6 plan management, subnet hierarchy, IP lifecycle, VLAN and DNS/DHCP integration. teemIP is now maintained by the teemIP SAS founding team: Christophe Naud (original creator), Martin de Laval and Quentin Ville. The company is being officially incorporated in July 2026. The project remains open source under AGPL v3. Professional support, integration services and subscriptions: https://www.teemip.com
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    Downloads: 72 This Week
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  • 8
    Open Tax Solver

    Open Tax Solver

    Calculates income tax form entries, helps do your taxes.

    OTS is a safe, secure, easy-to-use program for calculating Tax Return Form entries, and determining your tax-owed or refund-due, for Federal or State personal income taxes. Includes updated versions for US 1040, Schedules A, B, C, D, and for several states. OTS provides both graphical and textual interfaces for quickly filing out your tax forms. --- Best way to download the correct version for your platform -- go to the OTS WEBSITE: =====> https://opentaxsolver.sourceforge.net/
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    Downloads: 74 This Week
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  • 9
    CEmu emulator

    CEmu emulator

    Third-party TI-84 Plus CE / TI-83 Premium CE emulator

    Developer-oriented emulator of the eZ80-based TI-84 Plus CE / TI-83 Premium CE calculators. CEmu is a third-party TI-84 Plus CE / TI-83 Premium CE calculator emulator, focused on developer features. The core is programmed in C and the GUI in C++ with Qt, for performance and portability reasons. CEmu works natively on Windows, macOS, and Linux! Easy setup - get running by doing a one-time-only connection of your calculator! Accurate and fast emulation. Customizable speed/throttling. Resizable calculator screen. "Always-on-top" window option. Screen capture (PNG). Screen recording (animated PNG). File sending/receiving (not for Apps/OS yet). Multiple keybinding presets. Emulation states for efficient saving / restoring. Color skins (like the real devices). Available in English, French, Spanish, and Dutch.
    Downloads: 11 This Week
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    GestioIP IPAM - IP address management
    An automated, Web based IP address management (IPAM) software. It features powerful search and filter functions for both networks and host, as well as many tools (e.g. a subnet calculator) helping Administrators to plan and handle complex IP networks
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    Downloads: 54 This Week
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  • 11
    Precise Calculator
    Precise Calculator has arbitrary precision and can calculate with complex numbers, fractions, vectors and matrices. Has more than 150 mathematical functions and statistical functions and is programmable (if, goto, print, return, for).
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    Downloads: 41 This Week
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  • 12
    WP 34s

    WP 34s

    Scientific/engineering firmware repurposing HP business calculators!

    This project has created scientific firmware for the HP-20b and HP-30b business calculators. WP 34S turns either of these calculators into a powerful keystroke programmable scientific device. According to our customers, it's the most powerful and fastest RPN scientific pocket calculator ever built. WP 34S is alive and stable since 2011. We have succeeded in satisfying the most picky users - read about their experiences on http://www.hpmuseum.org/forum/forum-8.html. Since 2014, WP 34S runs in version 3.3. Our customers confirm its documentation is excellent and comprehensive (see feedback); a full-color printed edition is available from https://www.amazon.com/dp/153366238X since 2018-10-15. Alternatively, you can get a personalized pdf-manual for a ≥ 9 US$ donation here. We have also produced the WP 31S which is derived from the WP 34S source code. This is an entry-level scientific calculator. Its printed manual is available from https://www.amazon.com/dp/1499231164 .
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    Downloads: 30 This Week
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  • 13
    Numi

    Numi

    Beautiful calculator app for macOS

    Numi is a handy calculator app for macOS. It allows you to describe tasks naturally and instantly get an answer. For example, $20 in euro - 5% discount or today + 2 weeks.
    Downloads: 5 This Week
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  • 14

    calc: C-style arbitrary precision system

    Calc: arbitrary precision C-like arithmetic & calculator

    Calc is arbitrary precision C-like arithmetic system that is a calculator, an algorithm prototyper and mathematical research tool. Calc comes with a rich set of builtin mathematical and programmatic functions.
    Downloads: 21 This Week
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  • 15
    Position Sizer

    Position Sizer

    Risk-based position size calculation tool with extra features

    Position Sizer is a utility panel for MetaTrader 4 and MetaTrader 5 platforms that lets you easily calculate position sizes for trades based on risk tolerance, stop-loss, account size, and the current market conditions. It can be configured and customized in multiple ways: https://www.earnforex.com/metatrader-expert-advisors/Position-Sizer/
    Downloads: 54 This Week
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  • 16
    4tH compiler

    4tH compiler

    A friendly Forth compiler with a little difference

    4tH is a Forth compiler with a little difference. Instead of the standard Forth engine it features a conventional compiler. 4tH is a very small compiler that can create bytecode, C-embeddable bytecode, standalone executables, but also works fine as a scripting language. It supports about 95% of the ANS Forth CORE wordset and features conditional compilation, pipes, files, assertions, forward declarations, enumerations, structures, suspended execution, recursion, include files, etc. It comes with an RPN calculator, BASIC interpreter, line editor, preprocessor, compiler, decompiler, C-source generator, a virtual machine, and a multitasking environment.
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    Downloads: 51 This Week
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  • 17
    GraphCalc is a very gui graphing calculator. It has been called a good replacement for a TI-85. It is a must for any high school math student.
    Downloads: 11 This Week
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  • 18
    This is a Hash Calculating tool that calculates MD2,MD5,SHA-1,SHA-256,SHA-384,SHA-512 hash of text or a file. This has GUI developed in java swings.All it needs is sun jre installed.
    Downloads: 17 This Week
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  • 19
    RPNcalculator
    Nice looking calculator using Reverse Polish Notation (RPN) written for Windows. It supports DEC, HEX, BIN, OCT numbers, GRAD, RAD and DEG.
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    Downloads: 10 This Week
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  • 20
    Advanced Trigonometry Calculator

    Advanced Trigonometry Calculator

    Open-source C/C++ math engine for advanced scientific computing

    Advanced Trigonometry Calculator (ATC) is an open-source mathematical computing engine written mainly in C/C++. Created in 2011 and maintained by Renato Alexandre dos Santos Freitas, ATC is designed as a practical Windows desktop application for advanced calculations, automation, and technical problem solving. ATC supports equation solving, polynomial tools, complex numbers, matrix calculations, statistics, physics, geometry, unit conversions, DSP/FFT operations, and scripting. It can also process batch TXT files, making it useful for repeatable calculations and automated workflows. The project also includes ATC Online Alpha, a WebAssembly-based version that brings parts of the ATC engine to the web. ATC is released under the GPLv3 license and is made in Portugal.
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    Downloads: 16 This Week
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  • 21
    Hash Calculator

    Hash Calculator

    Simple Hash Calculator

    This program will allow you to manually type, or browse for a file on your system. You will then be able to generate a MD5, SHA256, or SHA512 hash digest of this file. This program requires no installation and is intended to be a simple, lightweight program. This is also my first open source project!
    Downloads: 25 This Week
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  • 22
    Finanx 12c

    Finanx 12c

    Financial Calculator

    The Finanx 12c is a free software that mimics the HP-12C financial calculator. This software was developed for educational purposes. IT'S NOT RECOMMENDED using this calculator for professional calculations. If you find any bugs, please, let me know. Click "Bugs" in the menu bar to report bugs found.
    Downloads: 9 This Week
    Last Update:
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  • 23
    Gordian Knot started out as a simple bitrate calculator for DivX encoding but has evolved to become an integrated package or tool for the entire process of DivX/XviD encoding.
    Downloads: 10 This Week
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  • 24
    IP Subnet Calculator
    Administration of large networks could be a very time-consuming work. So this program should represent a comfortable solution for calculating subnets in IPv4-networks. First fo all it is designed for Windows but also executable under Linux/Mono.
    Downloads: 20 This Week
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  • 25
    fHash

    fHash

    A files hash calculator for Windows and macOS.

    An open source files hash calculator for Windows and macOS. * MD5, SHA1, SHA256 and SHA512. * Drag & drop. * Integrated with context menu in Explorer/Finder. * Support Windows 7 and later. * Support macOS 13 and later, with universal binary. * Support Dark Mode. * English and Simplified Chinese UI. The icon "希" is from hash in Chinese "哈希".
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    Downloads: 19 This Week
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